Method of preparing phosphate esters using metal sulfate catalysts

ABSTRACT

HALOALKYL PHOSPHATE AND PHOSPHITE ESTERS ARE PREPARED BY REACTING AN EPOXIDE WITH A PHOSPHORUS OXYHALIDE OR HALO PHOSPHITE WITH AN EPOXIDE IN THE PRESENCE OF SMALL AMOUNTS OF FREE WATER OR UP TO 18 MOLES OF WATER OF CRYS TALLIZATION PERSENT IN A SULFATE OF A DI-, TRI-, OR TETRAVALENT METAL HAVING AN ATOMIC NUMBER FROM 12-82, INCLUSIVE. THE TRIS(HALOALKYL) PHOSPHATE AND PHOSPHITE ESTERS HAVE KNOWN UTILITY AS FIRE-RETARDANT PLASTICIZERS FOR VINYL AND CELLULOSE ESTER POLYMERS.

United States Patent 3,557,260 METHOD OF PREPARING PHOSPHATE ESTERS USING METAL SULFATE CATALYSTS Arthur E. Gurgiolo, Lake Jackson, Tex., assignor to The Dow Chemical Company, Midland, Mich., a corporation of Delaware N0 Drawing. Filed May 2, 1967, Ser. No. 635,343

Int. Cl. C07f 9/08, 9/16 US. Cl. 260-977 13 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a method of making phosphorus and phosphoric haloalkyl esters by reacting a compound of the formula P(O) X where X is a halogen atom, with a vicinal epoxide in the presence of from about .05 to about by weight based on the phosphorus compound of a sulfate of a di-, trior tetravalent metal of atomic number 12-82, inclusive, and small amount of free water or up to about 18 moles of water of crystallization as the catalyst.

The known processes for preparing haloalkyl phosphate and phosphite esters by reacting POX or PX where X is a halogen, with an epoxide are conducted under anhydrous conditions with water-sensitive metal halides. The presence of moisture is deleterious because it can hydrolyze some of the catalyst or the phosphoruscontaining halide reactant. In many instances the use of metal halide catalysts also accelerates the formation of by-products if the temperature at which the reacion is run is raised to about 7080 C. or higher, and in certain other instances it is necessary to wash the catalyst and by-products from the reaction mixture in order to obtain esters of low acid number.

I have found that the esterification of compounds of the formula P(O) X with epoxides can be catalyzed with sulfates of metals of atomic number 1282, inclusive, if traces of free water or up to 18 moles of water of crystallization per mole of catalyst are included in the system. In the absence of trace amounts of free water or water of crystallization, the sulfates displayed substantially no catalytic activity. One run made with a mole of POCl 3.3 moles of ethylene oxide and 1% by weight baset on the weight of POCl of anhydrous Ti(SO resulted in the production of a light brown product with an unsatisfactory acid number.

The amount of free water added to the system can range from 500 ppm. to about 1.0% based on the weight of catalyst. However, if the catalyst contains Water of crystallization, no free Water need be added, and preferably should be avoided. Most of the sulfates of the di-, triand tetravalent metals of atomic number 12 to 82, inclusive, have the additional advantage in that they are are not hygroscopic and therefore do not require special storage and handling. Mose of these catalysts produce light colored, low acid number phosphate and phosphite esters with a minimum of by-products at temperatures as high as 130 C. Further, most of the catalysts of this invention are substantially insoluble in the reaction mixture, so that filtration removes the catalyst from the mixture after the reaction is completed.

3,557,260 Patented Jan. 19, 1971 'ice Representative catalysts are TiOSO Ti(SO -9H O, MgSO '7H O, CI'2(SO4)3 'XHZO, CIK(SO4)2 121 120, Ce(SO MnSO -H O, ZnSO -4H O, ZnSO SnSQ PbSO HgSO CaSO -2H O and Al (SO Although amounts of catalyst, based on the phosphorus halide, can range from about .05 to about 5% by weight, the preferred amount is .5 to about 1% by weight. Below 0.1% catalyst, the reaction tends to slow down slightly and there appears to be no practical further increase in reaction rate at concentrations much above 1% by weight.

The reaction will proceed at temperatures of 25 to 130 C. At the low temperature, the reaction is fairly slow and above 130 C. there is a tendency with some of the catalysts to cause color formation. Therefore, the preferred reaction temperature is from about 60 to 120 C.

The reactants of the generic formula P(O) X can be POF3, POC13, POBI3, PO13, PF3, PC13, PBI'3, P13 or the phosphorus atom can bear two or three different halogen atoms. Mixtures of the phosphorus halogen containing compounds can be used.

The epoxides which can be reacted with the phosphorus halogen-containing compounds have the generic formula in which R and R each, independently, can be hydrogen, an alkyl group, a haloalkyl group, an allyloxyalkoxymethyl group, an allyloxy haloalkoxymethyl group, or an allyoxymethyl group. The total carbon content of the epoxide can range from 2 to about 57, and the R and R groups can contain carbon to carbon unsaturation.

Representative epoxides include, but are not limited to, ethylene oxide, 1,2-propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, 1,2-, or 2,3-pentylene oxide, 1,2-, or 2,3- and 3,4-n-hexylene oxide, styrene oxide, methyl styrene oxide, ring halogenated styrene oxides, allyl glycidyl ether, allyloxypropyl glycidyl ether, epichlorohydrin, epibromohydrin, epoxidized tall oil, epoxidized linseed oil, epoxidized cottonseed oil, or mono [glycidyl] ether of bisphenol A. Any epoxy compound containing up to abut 57 carbon atoms is operative.

The proportion of reactants should be at least 3 epoxy equivalents per mole of P(O) X and preferably a slight excess of epoxy compound is used.

Typical catalysts are sulfates of Mg, Ca, Ba, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, Re, Os, Al, Ge, Ga, Sn, Pb, and Sb. Sulfates of other metals having valents of 2-4, inclusive, and an atomic number of 1282 are operable. The catalysts can be defined generically by the formula M (SO ZH O, where M is a metal having a valence of 2 to 4 inclusive, and an atomic number of 12-82, x is an integer of from 1 to 2, y is an integer of from 1 to 3, and Z ranges from 500 parts per million based on the catalyst weight to 18 moles of water of crystallization. It should be understood that these metal sulfates do not have the same activity and that their efficiency varies. The preferred catalysts are the sulfates of Ti, Sn, Al and Zr.

The examples which follow are intended as illustrations of the invention, not as limitations. All parts are by weight unless otherwise specifically indicated.

EXAMPLE 1 A SOO-ml. reactor equipped with a stirrer, thermometer, condenser, separator funnel and N inlet was purged with nitrogen. Then, 66 parts by weight of POCl and 1.5 weight parts of TiOSO -2H O were added to the flask and weight parts of propylene oxide were fed to the POCl -catalyst mixture over a 30 minute period. The

EXAMPLE 2 A series of runs with POCl and ethylene oxide was made by the procedural steps described in Example 1. The catalyst, its concentration, the molar ratios of reactants, the time and the temperature of reaction and the data obtained in these runs are listed in Table I.

TiOSO -2H O, and the ethylene oxide was added gradually over a period of about one hour and then reacted for an additional hour at 8590 C. The reaction mixture was then cooled, filtered and flash distilled at 80 C. and mm. pressure. The Weight of light yellow tris(chloroethyl) phosphite recovered was 241 g. It had a refractive index of 1.4898 at 23 C. and an acid number of 4.3.

I claim:

1. The method which comprises commingling a phos phorus compound of the structure P(O) X wherein X is a halogen with a vicinal epoxide of the formula selected from the group consisting of ethylene oxide, propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide,

TAB LE I Catalyst Weight Reaction Reaction Weight Acid No. Moles P0 013 Percent temp. time, Of 0f epoxide Moles Type on PO Ch 0. hours product product 3. 64 1 TiOSOi 52 90 3 280 l 3. 4 1 Same- 4. 9 50-55 18 265 49 4 1 d0 .98 60-U0 4 280 0.3 4 1 '1i(SO-i)2-9Hg0 08 60-90 2. 5 27b 0 3. 87 1 'liO (S04) 05 90 72 220 00 3. 5 1 MgSO4-7HgO 98 90 2.5 257 2. 0 3.4 1 SnSO-r 52 85-90 2. 5 290 1. 0

None of the tris(chloroethyl) phosphate esters were Washed after completion of the reaction.

The quantity of catalyst in run 5 was just sufficient to form a saturated solution in POCl at 90 C.

In those cases Where TiOSO, and SnSO were used 500 p.p.m. of water based on catalyst weight were added to the catalyst before it was added to the POCI EXAMPLE 3 A series of runs was made by combining all ingredients at one time in a citrate bottle, flushing with nitrogen, capping the bottle and then holding at desired temperature levels for designated periods of time. Various epoxides and catalysts at several concentration levels were employed in the tests. Tabulated below are data for these 2,3-pentylene oxide, 1,2-n-hexylene oxide, 2,3-n-hexylene oxide, 3,4-n-hexylene oxide, styrene oxide, epichlorohydrin, epibromohydrin, allyloxypropylglycidyl ether, and monoglycidyl ether of bisphenol A, and a catalytic amount, up to about 5% by weight based on said phosphorus compound, of a sulfate of Al, Ca, Ti, Cr, Mn, Fe, Zn, Zr, Cd, Sn, Hg, Pb, and a double salt of Cr and an alkali metal, said reaction mixture containing from 500 p.p.m. to about 1% of free Water based on the Weight of the sulfate to about 18 moles of Water of crystallization in said sulfate, the reaction temperature of said method ranging from about 60 to about 130 C.

2. The method of claim 1 in which one of R and R is hydrogen and the other is a hydrogen or a hydrocarbon runs. group of from 1 to 2 carbon atoms.

TABLE II Catalyst Weight Reaction Weight percent tempcr- Reaction of PO C13, on ature, time, product, Color of Epoxide, moles moles Type PO01; hours grams product Run No 1. Propylene oxide, .86 25 0]?(5003-1120 52 70 30 85.5 Colorless. 2 do .25 CrK(SO4)g 12HgO 52 70 30 83. 8 Tinge of green. 3 do. 25 52 70 30 82. 6 Slightly yellow. 4 25 52 70 30 80.3 Colorless. 5 25 52 70 30 74. 4 D0. 6 25 PbS04 52 72 86 Light yellow. 7 52 (i0 72 93 Slightly dark. 3, 52 G0 72 161. 9 Slightly yellow. 9. Epichlorohydrin, 1.G2 52 (i0 72 221 Do. 10 Epibromohydrin, .8. 52 60 72 157 Slightly dark. 11 2, 3-butylene oxide, 1.46... 52 (i0 72 181 D0. 12 Allyl glycidyl ether, 1.67 52 60 72 260 Slightly yellow. 13 Allyloxypropyl glycidyl ether, .76 52 60 72 149 Slightly dark.

lene oxide. 17 52 60 72 244 Colorless.

52 60 72 244 Slightly yellow. 52 60 72 243 Do. 52 30 86 D0. .25 CaSOi-ZH .52 70 30 74.4 Do. 25 (A1)2(SO4)3 52 70 30 87. 6 Colorless.

1 500 p.p.m. water added with catalyst. Run 14 was made with ml. toluene, Run 15 with 100 ml. ethylene dichloride and Run 16 with 100 ml. dioxane, as diluents. The diluent in each instance was 7 added to the POCl EXAMPLE 4 The equipment described in Example 1 was employed for reacting one mole of PCl with 3.4 moles of ethylene oxide. To the PCl was added .52 wt. percent of 3. The method of claim 1 in which the epoxide is 6 7. The method of claim 1 in which the epoxide is allyl- 13. The method of claim 1 in which the catalyst is oxypropyl glycidyl ether. SnSO 8. The method of claim 1 in which the phosphorus References Cited compound is POCl 9. The method of claim 1 in which the phosphorus 5 UNITED STATES PATENTS compound is Pcl3 1,936,985 11/1933 Lommel et al. 260-977X 10. The method of claim 1 in which the catalyst is TiOSO in an amount ranging from about 0.1 to about CHARLES PARKER Primary Exammer 5% by weight based on the phosphorus compound. A. H. SUTTO, Assistant Examiner 11. The method of claim 10 in which the catalyst content ranges from about 0.1 to about 1%. 10

12. The method of claim 1 in which the catalyst is a double salt of Cr and an alkali metal. 

